Blade extension for rotor blade in wind turbine

ABSTRACT

A blade extension for a rotor blade and a rotor blade assembly for a wind turbine are disclosed. The rotor blade assembly includes a rotor blade having exterior surfaces defining a pressure side, a suction side, a leading edge, and a trailing edge each extending in a generally span-wise direction between a tip and a root. The rotor blade assembly further includes a blade extension including a first panel and an opposed second panel. Each of the first panel and the second panel includes an interior surface and an exterior surface each extending between a proximal end and a distal end. The distal end of each of the first panel and the second panel is spaced apart from the rotor blade in a generally chord-wise direction in a standard operation position.

FIELD OF THE INVENTION

The present disclosure relates in general to wind turbine rotor blades,and more particularly to blade extensions for the rotor blades.

BACKGROUND OF THE INVENTION

Wind power is considered one of the cleanest, most environmentallyfriendly energy sources presently available, and wind turbines havegained increased attention in this regard. A modern wind turbinetypically includes a tower, generator, gearbox, nacelle, and one or morerotor blades. The rotor blades capture kinetic energy of wind usingknown airfoil principles. The rotor blades transmit the kinetic energyin the form of rotational energy so as to turn a shaft coupling therotor blades to a gearbox, or if a gearbox is not used, directly to thegenerator. The generator then converts the mechanical energy toelectrical energy that may be deployed to a utility grid.

Presently known wind turbine technology has lead to rotor blades thatare in general increasing in size, in order to become capable ofcapturing increased kinetic energy. However, as the size of a rotorblade increases, so does the weight. Such increased weight cannegatively impact the performance of a rotor blade and wind turbine ingeneral.

Further, present wind turbine technology has lead to the development offlaps and/or other suitable extensions which may be retrofitted to rotorblades. The extensions are typically formed from solid, one-piecedesigns, and are mounted on the rotor blades to increase the rotor bladesurface area and thus increase the lift. However, such extensions addweight to the rotor blade. As blade extensions increase in size toaccommodate increases in rotor blade size, the added weight of the bladeextensions can negatively impact the performance of a rotor blade andwind turbine in general.

Additionally, wind turbines typically require braking systems forbraking the rotor blades during certain periods in the operation of thewind turbine. However, such braking systems can, especially due to theincreasing size of rotor blades, be prohibitively costly and heavy.

Thus, an improved rotor blade assembly would be advantageous. Forexample, a rotor blade assembly that includes an improved bladeextension would be desired in the art. In particular, a rotor bladeassembly that includes a blade extension having lightweight featuresand/or braking features would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one embodiment, a rotor blade assembly for a wind turbine isdisclosed. The rotor blade assembly includes a rotor blade havingexterior surfaces defining a pressure side, a suction side, a leadingedge, and a trailing edge each extending in a generally span-wisedirection between a tip and a root. The rotor blade assembly furtherincludes a blade extension including a first panel and an opposed secondpanel. Each of the first panel and the second panel includes an interiorsurface and an exterior surface each extending between a proximal endand a distal end. The distal end of each of the first panel and thesecond panel is spaced apart from the rotor blade in a generallychord-wise direction in a standard operation position.

In another embodiment, a blade extension for a rotor blade in a windturbine is disclosed. The blade extension includes a first panel and anopposed second panel. Each of the first panel and the second panelincludes an interior surface and an exterior surface each extendingbetween a proximal end and a distal end. The distal end of each of thefirst panel and the second panel is configured to be spaced apart fromthe rotor blade in a generally chord-wise direction in a standardoperation position.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a side view of a wind turbine according to one embodiment ofthe present disclosure;

FIG. 2 is a top perspective view of a rotor blade assembly according toone embodiment of the present disclosure;

FIG. 3 is a top perspective view of a rotor blade assembly according toanother embodiment of the present disclosure;

FIG. 4 is a cross-sectional view of a rotor blade assembly according toone embodiment of the present disclosure;

FIG. 5 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure;

FIG. 6 is a cross-sectional view of a rotor blade assembly according toanother embodiment of the present disclosure;

FIG. 7 is a cross-sectional view of a rotor blade assembly in a standardoperation position according to one embodiment of the presentdisclosure;

FIG. 8 is a cross-sectional view of the rotor blade assembly of FIG. 7in a ancillary position according to one embodiment of the presentdisclosure;

FIG. 9 is a cross-sectional view of a rotor blade assembly in a standardoperation position according to another embodiment of the presentdisclosure;

FIG. 10 is a cross-sectional view of the rotor blade assembly of FIG. 9in an ancillary position according to one embodiment of the presentdisclosure;

FIG. 11 is a cross-sectional view of a rotor blade assembly in astandard operation position according to another embodiment of thepresent disclosure;

FIG. 12 is a cross-sectional view of the rotor blade assembly of FIG. 11in an ancillary position according to one embodiment of the presentdisclosure;

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention,one or more examples of which are illustrated in the drawings. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations can be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment can be used with another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

FIG. 1 illustrates a wind turbine 10 of conventional construction. Thewind turbine 10 includes a tower 12 with a nacelle 14 mounted thereon. Aplurality of rotor blades 16 are mounted to a rotor hub 18, which is inturn connected to a main flange that turns a main rotor shaft. The windturbine power generation and control components are housed within thenacelle 14. The view of FIG. 1 is provided for illustrative purposesonly to place the present invention in an exemplary field of use. Itshould be appreciated that the invention is not limited to anyparticular type of wind turbine configuration.

Referring to FIGS. 2 through 12, a rotor blade 16 according to thepresent disclosure may include exterior surfaces defining a pressureside 22, a suction side 24, a leading edge 26, and a trailing edge 28.The pressure side 22 and suction side 24 may each extend between theleading edge 26 and the trailing edge 28. The exterior surfaces mayextend between a blade tip 32 and a blade root 34 in a generallyspan-wise direction, as discussed below.

One or more of the pressure side 22, suction side 24, the leading edge26 and/or the trailing edge 28 may be generally aerodynamic surfaceshaving generally aerodynamic contours, as is generally known in the art.For example, FIGS. 4 through 12 illustrate various embodiments of arotor blade 16 wherein the pressure side 22, suction side 24, theleading edge 26 and the trailing edge 28 have generally aerodynamicsurfaces having generally aerodynamic contours and thus forming atypically know airfoil cross-sectional profile.

In some embodiments, the rotor blade 16 may include a plurality ofindividual blade segments aligned in an end-to-end order from the bladetip 32 to the blade root 34. Each of the individual blade segments maybe uniquely configured so that the plurality of blade segments define acomplete rotor blade 16 having a designed aerodynamic profile, length,and other desired characteristics. For example, each of the bladesegments may have an aerodynamic profile that corresponds to theaerodynamic profile of adjacent blade segments. Thus, the aerodynamicprofiles of the blade segments may form a continuous aerodynamic profileof the rotor blade 16. Alternatively, the rotor blade 16 may be formedas a singular, unitary blade having the designed aerodynamic profile,length, and other desired characteristics.

The rotor blade 16 may, in exemplary embodiments, be curved. Curving ofthe rotor blade 16 may entail bending the rotor blade 16 in a generallyflapwise direction and/or in a generally edgewise direction. Theflapwise direction may generally be construed as the direction (or theopposite direction) in which the aerodynamic lift acts on the rotorblade 16. The edgewise direction is generally perpendicular to theflapwise direction. Flapwise curvature of the rotor blade 16 is alsoknown as pre-bend, while edgewise curvature is also known as sweep.Thus, a curved rotor blade 16 may be pre-bent and/or swept. Curving mayenable the rotor blade 16 to better withstand flapwise and edgewiseloads during operation of the wind turbine 10, and may further provideclearance for the rotor blade 16 from the tower 12 during operation ofthe wind turbine 10.

The rotor blade 16 may further define a chord 42 and a span 44 extendingin chord-wise and span-wise directions, respectively. As shown in FIGS.2 through 5, the chord 42 may vary throughout the span 44 of the rotorblade 16. Thus, as discussed below, a local chord 46 may be defined forthe rotor blade 16 at any point on the rotor blade 16 along the span 44.Further, the rotor blade 16 may define a maximum chord 48, as shown.

Additionally, the rotor blade 16 may define an inner board area 52 andan outer board area 54. The inner board area 52 may be a span-wiseportion of the rotor blade 16 extending from the root 34. For example,the inner board area 52 may, in some embodiments, include approximately33%, 40%, 50%, 60%, 67%, or any percentage or range of percentagestherebetween, or any other suitable percentage or range of percentages,of the span 44 from the root 34. The outer board area 54 may be aspan-wise portion of the rotor blade 16 extending from the tip 32, andmay in some embodiments include the remaining portion of the rotor blade16 between the inner board area 52 and the tip 32. Additionally oralternatively, the outer board area 54 may, in some embodiments, includeapproximately 33%, 40%, 50%, 60%, 67%, or any percentage or range ofpercentages therebetween, or any other suitable percentage or range ofpercentages, of the span 44 from the tip 32.

One or more structural components may be included within the rotor blade16 to provide structural support to the rotor blade 16. For example,FIGS. 4 through 12 illustrate a shear web 62 extending between two sparcaps 64. The shear web 62 and spar caps 64 may extend through the rotorblade 16 or any portion thereof in the generally span-wise direction.The external surfaces defining the pressure side 22 and suction side 24may include, or may cover, the spar caps 64.

As illustrated in FIGS. 2 through 12, the present disclosure may furtherbe directed to a rotor blade assembly 100. A rotor blade assembly 100according to the present disclosure may include a rotor blade 16 and ablade extension 110. The blade extension 110 includes two opposedpanels. Each panel 112, 114 includes an interior surface 116 and anexterior surface 118. The panels 112, 114 are opposed, such that theinterior surfaces 116 of the panels face each other and the exteriorsurfaces 118 face away from one another.

Each panel 112, 114 or any portion thereof may, in some embodiments,have a generally aerodynamic contour. For example, the outer surface 118may have a generally aerodynamic contour. Further, in some embodiments,the outer surface 118 may define a generally continuous aerodynamicsurface with an exterior surface, such as the pressure side 22 orsuction side 24, of a rotor blade 16. A generally continuous aerodynamicsurface is a surface that has a generally continuous aerodynamiccontour. Thus, when two surfaces define a generally continuousaerodynamic surface, there is relatively little interruption in theaerodynamic contour at the intersection of the two surfaces. Suchcontinuous aerodynamic contour may particularly occur in embodimentswherein the panels 112, 114 are fixed, and/or in embodiments wherein thepanels 112, 114 are movable and in a normal operation position, and/orin embodiments wherein the panels 112, 114 are movable and in anancillary position, as discussed below.

In other embodiments, the panels 112, 114, such as the exterior surfaces118 thereof, or any portions thereof, may have any other suitablecontours, which may be planer, curvi-planer, or otherwise.

As shown, each panel 112, 114 may further extend between a proximal end120 and a distal end 122. The proximal end 120 may be the end that ismounted to the rotor blade 16 and/or remains relatively closer to therotor blade 16 when the panel 112, 114 is moved to an ancillaryposition, as discussed below. The distal end 122 may be the end that isnot mounted to the rotor blade 16 and/or remains relatively farther awayfrom the rotor blade 16 when the panel 112, 114 is moved to an ancillaryposition, as discussed below. The interior surface 116 and exteriorsurface 118 of each panel 112, 114 may each extend between a proximalend 120 and a distal end 122.

Each panel 112, 114 may further extend through any suitable span-wiseportion of the rotor blade 16, and may thus have any suitable lengthrelative to the span 44. For example, a panel 112, 114 may extend fromthe root 34 towards the tip 32 as shown in FIG. 2. Alternatively, thepanel 112, 114 may be spaced from the root 34 as shown in FIG. 3.Further, a panel 112, 114 may be disposed entirely within the innerboard area 52 as shown in FIG. 2, within both the inner board area 52and outer board area 54, or entirely within the outer board area 54 asshown in FIG. 3.

Further, a panel 112, 114 may overlap any suitable portion of a rotorblade 16, as shown in FIGS. 4 through 12. Overlap may be determinedbased on any suitable cross-sectional profile of the rotor blade 16 at aspan-wise location wherein the blade extension 110 is mounted to therotor blade 16, and may be determined relative to the local chord 46.For example, a panel 112 and/or a panel 114 may overlap approximately70%, approximately 60%, approximately 50%, approximately 40%,approximately 30%, between approximately 0% and approximately 70%,between approximately 0% and approximately 60%, between approximately 0%and approximately 50%, or between approximately 0% and approximately40%, or any other suitable percentage, range, or sub-range thereof, ofthe local chord 46.

In some embodiments, as shown in FIGS. 4 through 10, the proximal end120 of a panel 112, 114 may be mounted to the rotor blade 16, such as toan exterior surface thereof. The proximal end 120 may in someembodiments be mounted through the use of, for example, a suitableadhesive or a suitable brazing or welding technique, or may be mountedthrough the use of, for example, suitable mechanical fasteners such asscrews, nails, rivets, nut-bolt combinations, etc. In these embodiments,the panel 112, 114 may be fixed with respect to the rotor blade 16, asdiscussed below and shown in FIGS. 4 through 6. In other embodiments,the proximal end 120 may be mounted through the use of a pin or othersuitable device or apparatus that allows the panel 112, 114 to move,such as rotate, with respect to the rotor blade 16, as discussed belowand shown in FIGS. 7 through 10. In still other embodiments, theproximal end 120 may be free from, and not mounted to, the rotor blade16, such that the panel 112, 114 may move, such as slide, with respectto the rotor blade 16, as discussed below and shown in FIGS. 11 and 12.

As mentioned, the proximal end 120 of a panel 112, 114 may in someembodiments be mounted to the rotor blade 16, such as to an exteriorsurface thereof. For example, the first panel 112 may be mounted to thesuction side 24 as shown in FIGS. 4 through 11, or may be mounted to thepressure side 22, leading edge 26, or trailing edge 28. The second panel114 may be mounted to the trailing edge 28 as shown in FIGS. 4 and 7through 8, the pressure side 22 as shown in FIGS. 5, 6, 9, and 10, ormay be mounted to the suction side 24 or leading edge 26.

The distal end 122 of a panel 112, 114 may be spaced apart from therotor blade 16 when the panel is in a standard operation position. Forexample, as shown in FIGS. 4 through 7, 9 and 11, the distal end 122 maybe spaced apart in the generally chord-wise direction (along the chord42 or local chord 46). The standard operation position may be the fixedposition, or may be a standard operation position for a movable panel112, 114, discussed below. The distal end 122 may in some embodimentsremain spaced from the rotor blade 16 when in an ancillary position, asshown in FIGS. 8, 10, and 12, or may be in alignment with the rotorblade 16 in the chord-wise direction when in the ancillary position,discussed below.

As shown, a blade extension 110 according to the present disclosure,such as the first panel 112 and second panel 114 thereof, may provideand define extended exterior surfaces for the rotor blade 16. Forexample, as shown in FIGS. 4 through 12, the exterior surface 118 of thefirst panel 112 may define an extended suction side 134, and theexterior surface 118 of the second panel 114 may provide an extendedpressure side 132. By extending the pressure side 22 and suction side 24of the rotor blade 16, the blade extension 110 may augment the liftcapacity, reduce the drag, and/or augment the lift to drag ratio of therotor blade 16 when in a fixed or standard operation position.

Additionally, in some embodiments as shown in FIGS. 4 through 10, theblade extension 110, such as the first panel 112 and second panel 114thereof, may define an extended trailing edge 138. Thus, the panels 112,114 may in these embodiments be spaced from the leading edge 26 in thechord-wise direction. One or both of the panels 112, 114 may still,however, overlap a portion of the rotor blade 16. In other embodimentsas shown in FIGS. 11 through 12, the blade extension 110, such as thefirst panel 112 and second panel 114 thereof, may define an extendedleading edge 136. Thus, the panels 112, 114 may in these embodiments bespaced from the trailing edge 28 in the chord-wise direction. One orboth of the panels 112, 114 may still, however, overlap a portion of therotor blade 16.

Each panel 112, 114 of a blade extension 110 according to the presentdisclosure may be formed from any suitable materials. In someembodiments, for example, a panel 112, 114 may include a core 140, asshown in FIGS. 4 through 12. Further, in some embodiments, a panel 112,114 may include a cover 142, as shown in FIG. 4. The cover 142 mayenclose at least a portion of the core 140, and may thus form theinterior surface 116 and/or exterior surface 118 of a panel 112, 114, asshown. The core 140 of a panel 112, 114 may be formed from, for example,carbon fiber, fiberglass, hardened foam, or any other suitable material.The material utilized to form a core 140 may preferably be lightweight,and may further preferably be suitably rigid to maintain its structureduring use in a wind turbine 10. The cover 142 of a panel 112, 114 maybe formed from fiberglass, aluminum, fabric, or any other suitablematerial. The fabric may, in some embodiments, be “doped” or treatedsuch that it is suitably rigid. Similar to the core 140, the materialutilized to form a cover 142 may preferably be lightweight, and mayfurther preferably be suitably rigid to maintain its structure duringuse in a wind turbine 10.

In some embodiments, as shown in FIG. 4, each of the first panel 112 andsecond panel 114 may include a cover 142. Further, in some embodimentsas shown, the covers 142 of the panel 112, 114 may be connected, thusforming a single integral cover 142. The integral cover 142 may extendbetween the first panel 112 and second panel 114 at any suitablelocation along the panels 112, 114. For example, in some embodiments,the cover 142 extends between the distal end 122 of the first panel 112and the distal end 122 of the second panel 114, and may thus form theextended trailing edge 138 as shown in FIG. 4 or the extended leadingedge 136. In other embodiments, however, the covers 142 of the firstpanel 112 and second panel 114 may be separate from each other.

As further shown in FIG. 4, a spring 144 may be connected between thecover 142 and a surface of the rotor blade 16, such as the pressure side22, suction side 24, leading edge 26, or trailing edge 28. The spring144 may provide a tensioning force to the cover 142, to ensure that thecover 142 remains taught during operation of the wind turbine 100.Additionally, in embodiments wherein the blade extension 110 is movableas discussed herein, the spring 144 may stretch and compress as requiredto maintain the taughtness of the cover 142.

In some embodiments, as shown in FIGS. 5 and 6, one or more structuralmembers may be included in a blade extension 110. The structural membersmay be mounted one or both panels 112, 114 and/or to the rotor blade 16to provide structural support to and between the panels 112, 114. Astructural member may thus extend between and connect the first panel112 and second panel 114, or may extend between and connect one of thepanels 112, 114 and an external surface of the rotor blade 16.Structural members may be, for example, rods, wedges, or webs, asdiscussed below, or any other suitable members that provide structuralsupport.

For example, in some embodiments as shown in FIG. 5, a blade extension110 may include one or more rods 152 and/or one or more wedges 154. Arod 152 may extend at any suitable direction and at any suitablelocation between the first panel 112 and second panel 114 or between oneof the panels 112, 114 and an external surface of the rotor blade 16. Insome embodiments, a rod 152 extending between the first panel 112 andsecond panel 114 may be located at or adjacent to the distal ends 122 ofthe panels 112, 114, to provide structural support for the distal ends122. Further, in some embodiments, a plurality of rods 152 may bedisposed and spaced apart along the span 44 of the rotor blade 16 or anyportion thereof. A wedge 154 may extend at any suitable direction and atany suitable location between one of the panels 112, 114 and an externalsurface of the rotor blade 16. A wedge 154 may extend along a suitableportion of the span 44 of the rotor blade 16, and/or a plurality ofwedges 154 may be disposed and spaced apart along the span 44 of therotor blade 16 or any portion thereof.

In other embodiments as shown in FIG. 6, a blade extension 110 mayinclude a web 156. A web 156 may extend at any suitable direction and atany suitable location between the first panel 112 and second panel 114or between one of the panels 112, 114 and an external surface of therotor blade 16. In some embodiments, a web 156 extending between thefirst panel 112 and second panel 114 may be located at or adjacent tothe distal ends 122 of the panels 112, 114, to provide structuralsupport for the distal ends 122. A web 156 may extend along a suitableportion of the span 44 of the rotor blade 16, and/or a plurality of webs156 may be disposed and spaced apart along the span 44 of the rotorblade 16 or any portion thereof.

As discussed above, in some embodiments one or both of the first panel112 and the second panel 114 may be fixed, while in other embodimentsone or both of the first panel 112 and the second panel 114 may bemovable. For example, FIGS. 4 through 6 illustrate various embodimentswherein the first panel 112 and second panel 114 are fixed. When a panel112, 114 is fixed, it does not move relative to the rotor blade 16 otherthan due to external forces during operation of the wind turbine 10.Further, a panel 112, 114 according to the present disclosure may befixed in a standard operation position, as discussed below.

FIGS. 7 through 12 illustrate various embodiments wherein the firstpanel 112 and second panel 114 are movable relative to the rotor blade16. In general, a movable panel 112, 114 may be movable between astandard operation position, as shown in FIGS. 7, 9 and 11, and anancillary position, as shown in FIGS. 8, 10, and 12. A standardoperation position is a position that a panel 112, 114 may be in duringnormal operation of the wind turbine. Such position may allow the panel112, 114 to, for example, augment the lift capacity, reduce the drag,and/or augment the lift to drag ratio of the rotor blade 16 or provideanother suitable benefit to the rotor blade 16 during normal operation.An ancillary position is a position that a panel 112, 114 may be induring specified periods outside of normal operation of the wind turbine16. For example, an ancillary position may be a load shedding position,and a panel 112, 114 may be put in this position during periods ofincreased loading, or an ancillary position may be a braking position,and a panel 112, 114 may be put in this position during braking of awind turbine 10.

FIGS. 7 through 10 illustrate embodiments of movable panels 112, 114wherein the panels 112, 114 are pivotable. In these embodiments, theproximal end 120 of a panel 112, 114 may be pivotally mounted to therotor blade 16, and the distal end 122 may pivot with respect to theproximal end 120. Each panel 112, 114 may pivot in a direction from thepressure side 22 towards the suction side 24, as shown by both panels112, 114 in FIGS. 7 and 8 and the first panel 112 in FIGS. 9 and 10, ormay pivot in a direction from the suction side 24 towards the pressureside 22, as shown by the second panel in FIGS. 9 and 10.

FIGS. 11 and 12 illustrate embodiments of movable panels 112, 114wherein the panels 112, 114 are slidable. In these embodiments, theproximal end 120 and distal end 122 are both free from the rotor blade16, and the panel 112, 114 may slide relative to the rotor blade 16. Forexample, in the embodiment shown, each panel 112, 114 may slide relativeto the rotor blade 16 in the generally chord-wise direction over therespective suction side 24 and pressure side 22.

As shown in FIGS. 7 through 12, one or more actuators 160 may beincluded in the blade extension 110. Each actuator 160 may be connectedto a panel 112, 114, and may be actuable to move the panel 112, 114between a standard operation position and an ancillary position. Anactuator may be a pneumatic cylinder, a hydraulic cylinder, a gearbox,or any other suitable device that is actuable to move a panel 112, 114.

Thus, the present disclosure is advantageously directed to a bladeextension 110 and a rotor blade assembly 100 having improved features.For example, a blade extension 110 having a first panel 112 and a secondpanel 114 as discussed above may reduce the weight associated withsimilarly sized and previously known blade extensions 110, whileproviding similar lift augmentation, drag reduction, and/or lift to dragratio augmentation and/or other beneficial features to rotor blades 16.Such blade extensions 110 may further be retrofitted to existing rotorblade 16, as shown in FIGS. 2 though 12, or may be utilized in newlymanufactured rotor blades 16. Such blade extensions 110 may further, insome embodiments, include advantageously braking and/or load sheddingfeatures.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A rotor blade assembly for a wind turbine, the rotor blade assemblycomprising: a rotor blade having exterior surfaces defining a pressureside, a suction side, a leading edge, and a trailing edge each extendingin a generally span-wise direction between a tip and a root; and, ablade extension comprising a first panel and an opposed second panel,each of the first panel and the second panel comprising an interiorsurface and an exterior surface each extending between a proximal endand a distal end, the distal end of each of the first panel and thesecond panel spaced apart from the rotor blade in a generally chord-wisedirection in a standard operation position.
 2. The rotor blade assemblyof claim 1, wherein the blade extension defines an extended trailingedge.
 3. The rotor blade assembly of claim 1, wherein the bladeextension defines an extended leading edge.
 4. The rotor blade assemblyof claim 1, wherein each of the first panel and the second panelcomprises a core and a cover, the cover comprising the interior surfaceand the exterior surface.
 5. The rotor blade assembly of claim 4,wherein the cover of the first panel and the cover of the second panelare integral with each other, and wherein the integral cover extendsbetween the distal end of the first panel and the distal end of thesecond panel.
 6. The rotor blade assembly of claim 1, further comprisinga structural member extending between and connecting the first panel andthe second panel.
 7. The rotor blade assembly of claim 1, wherein theproximal end of the first panel is mounted to the suction side of therotor blade, and the proximal end of the second panel is mounted to thetrailing edge of the rotor blade.
 8. The rotor blade assembly of claim1, wherein the proximal end of the first panel is mounted to the suctionside of the rotor blade, and the proximal end of the second panel ismounted to the pressure side of the rotor blade.
 9. The rotor bladeassembly of claim 1, wherein at least one of the first panel or thesecond panel is fixed.
 10. The rotor blade assembly of claim 1, whereinat least one of the first panel or the second panel is movable.
 11. Therotor blade assembly of claim 10, wherein the at least one of the firstpanel or the second panel is pivotable.
 12. A wind turbine, comprising:a plurality of rotor blades, each of the plurality of rotor bladeshaving exterior surfaces defining a pressure side, a suction side, aleading edge and a trailing edge each extending in a generally span-wisedirection between a tip and a root; and, a blade extension comprising afirst panel and an opposed second panel, each of the first panel and thesecond panel comprising an interior surface and an exterior surface eachextending between a proximal end and a distal end, the distal end ofeach of the first panel and the second panel spaced apart from the rotorblade in a generally chord-wise direction in a standard operationposition.
 13. The wind turbine of claim 12, wherein the blade extensiondefines an extended trailing edge.
 14. The wind turbine of claim 12,wherein each of the first panel and the second panel comprises a coreand a cover, the cover comprising the interior surface and the exteriorsurface.
 15. The wind turbine of claim 12, further comprising astructural member extending between and connecting the first panel andthe second panel.
 16. The wind turbine of claim 12, wherein the proximalend of the first panel is mounted to the suction side of the rotorblade, and the proximal end of the second panel is mounted to thetrailing edge of the rotor blade.
 17. The wind turbine of claim 12,wherein the proximal end of the first panel is mounted to the suctionside of the rotor blade, and the proximal end of the second panel ismounted to the pressure side of the rotor blade.
 18. The wind turbine ofclaim 12, wherein at least one of the first panel or the second panel isfixed.
 19. The wind turbine of claim 12, wherein at least one of thefirst panel or the second panel is movable.
 20. A blade extension for arotor blade in a wind turbine, the blade extension comprising: a firstpanel and an opposed second panel, each of the first panel and thesecond panel comprising an interior surface and an exterior surface eachextending between a proximal end and a distal end, the distal end ofeach of the first panel and the second panel configured to be spacedapart from the rotor blade in a generally chord-wise direction in astandard operation position.